114 MORRIS LOEB 



to the experimental substantiation of a hypothesis reached by 

 inductive speculation. His synthetic researches were chiefly 

 carried out in test tubes, without overexact measurements 

 of reacting quantities, of temperature or other conditions. 

 The elaborate search for an optimum production of a given 

 compound, so familiar in recent inorganic work, did not ap- 

 peal to him, and he frequently emphasized his desire to point 

 out the directions in which complex compounds should be 

 sought, leaving their careful study to others. Working with 

 the simplest apparatus, almost exclusively in aqueous solu- 

 tions, he certainly produced an astonishing number of new 

 compounds, whose correlations he was able to point out with 

 considerable verisimilitude. Perhaps he missed a reaction 

 here and there; but few of his critics have been able to state 

 that they failed to find what he did, when they followed his 

 directions closely. As an analyst, he enriched us with some 

 elegant methods, which are not sufficiently emphasized in 

 textbooks: the determination of manganese as pyrophos- 

 phate; the use of mercuric oxide instead of a fixed alkali in 

 precipitating various acids with mercuric nitrate; improve- 

 ments in the estimation of bases as sulphates and oxalates; 

 the detection of cerium by means of bismuth tetroxide or 

 lead peroxide; the use of luteocobalt salts to characterize 

 various acids. The determination of metals by electrolysis, 

 the operation of difficult fusions downward instead of upward, 

 the use of a comparison tube in eudiometric measurements, 

 were all methods first published by him, and many methods 

 developed by others were due to his suggestions. In physics, 

 he early remedied defects in some types of galvanic cell, now 

 obsolete, and he devised improvements of considerable value 

 in the prism spectroscope. 



A curious departure from his customary work was his 

 reversion, late in life, to physiological chemistry, when he 



